title: Dissociation of hippocampal serotonin release and locomotor activity following pharmacological manipulations of the median raphe nucleus.
abstract: In vivo microdialysis was used to investigate the role of serotonin in the locomotor hyperactivity produced by injections of 8-hydroxy-2-(di-n-propylamino)tetralin (8-OHDPAT), muscimol and baclofen into the median raphe nucleus (MR) of unanesthetized rats. Intra-MR injections of the GABA(A) agonist muscimol (25 ng) resulted in a pronounced increase in locomotor activity which was accompanied by a 42% decrease in hippocampal serotonin release during the first hour following injection. Intra-MR injections of the GABA(B) agonist baclofen (125 ng) induced hyperactivity of a similar magnitude, but failed to affect hippocampal serotonin release. In contrast, the serotonin (5-HT1A) agonist 8-OHDPAT (5 microg) produced only a small effect on locomotor activity but reduced hippocampal serotonin output by 51%. These findings demonstrate that it is possible to dissociate the effects of intra-MR drug injections on locomotor activity and hippocampal 5-HT release and strongly support the view that nonserotonergic neurons in the paramedian tegmentum are importantly involved in the control of behavioral arousal.
authors.affiliation: Department of Psychology, The University of Illinois at Chicago, 60607-7137, USA.
authors.forename: I
authors.initials: I
authors.lastname: Shim
authors.forename: J
authors.initials: J
authors.lastname: Javaid
authors.forename: D
authors.initials: D
authors.lastname: Wirtshafter
mesh_terms: D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D000818:Animals; D001418:Baclofen / Q000494:pharmacology; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D018755:GABA Agonists / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism*; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D008297:Male; D017551:Microdialysis; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology*; D009118:Muscimol / Q000494:pharmacology; D011903:Raphe Nuclei / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000378:metabolism*; D017366:Serotonin Receptor Agonists / Q000494:pharmacology
chemical_list: D018755:GABA Agonists; D017366:Serotonin Receptor Agonists; D009118:Muscimol; D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D001418:Baclofen